In-Vehicle Execution Environment for Diagnostic Scripts on Heavy Commercial Vehicles.

Abstract: Today the importance and complexity of vehicle diagnostics are increasing and more systems uses remote diagnostics. Remote diagnostics involves an off-board server that uses a wireless connection to access the diagnostic services inside a vehicle on a remote location. Problems occur because of the remote connections limitations in speed and reliability. This can be solved by executing tasks on an Electrical Control Unit (ECU) inside the vehicle. However, implementing new software in an ECU is time consuming and expensive. An in-vehicle execution environment for diagnostic scripts can make it possible to send these tasks from the off-board systems and execute them on-board the vehicle. This thesis investigates that possibility. A set of requirements for an in-vehicle execution environment are identified together with important decisions that affects them. Restricting the diagnostic services to only passive scripts reduces the requirements. Using a higher abstraction level in the scripts to send diagnostic commands makes it easier to develop scripts, but requires more software to be implemented on the ECU. The choice of script engine is also important and a survey and evaluation of different script engines is performed. Python, Lua, mRuby and ChaiScript are compared and Lua is selected for an implementation used in a case study where the results are validated. This case study shows that the requirements are sufficient to create an in-vehicle execution environment that can execute advanced diagnostic tasks. An in-vehicle script executes more than eight times faster than the same task on the off-board system and decreases the amount of data in the remote communication. Development of a script is more than 20 times faster compared to the development of ECU system software. Before this in-vehicle execution environment can be used on a population of vehicles, investigations needs to be done regarding the requirements for the off- board systems and how the development and usage of scripts should be organized.